Electronic Excitation Energy Transfer between Different Types of Dye Molecules in a Porous Glass Matrix

The processes of electronic excitation energy transfer (EEET) between different types of dye molecules inserted into the matrix of a porous glass have been investigated. An extreme character of the dependence of the EEET efficiency on the size of pores has been revealed. The dependence of the fractal dimensionality of the distribution of dye molecules on the sizes of the pores has been determined. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 446–449, July–August, 2005.     

Synthesis of new derivatives of 5-alkyl-6-(2,6-dihalobenzyl)-2-(methylsulfanyl)pyrimidin-4(3<Emphasis Type=Italic>H</Emphasis>)-one and the features of their oxidation

The synthesis and features of the regioselective S-monomethylation of new 5-alkyl-6-(arylmethyl)-2-thioxo-2,3-dihydropyrimidin-4(1H)-ones were investigated, and also the character of the oxidative degradation of these compounds when treated with the system H₂O₂-AcOH.     

X-ray fluorescence determination of As, Bi, Co, Cu, Fe, Ni, Pb, Se, V and Zn in natural water and soil extracts after preconcentration of their pyrrolidinedithiocarbamates on cellulose filters

A simple method for the elements preconcentration on thin-layer paraffin-treated cellulose filters was proposed. It was found that pyrrolydinedithiocarbamates of As(III), Bi, Cd, Co, Cu, Fe(III), Ni, Pb, Se(IV), V(V) and Zn obtained after mixing of sample (3-5 ml min⁻¹) and reagent (0.7-1.0 ml min⁻¹) streams were quantitatively recovered from 100 ml sample. The sample acidity was adjusted to pH 4.8-5.2 for preconcentration of Cd, Co, Cu, Fe(III), Ni, Pb, V(V) and Zn, and to 2 M HCl for preconcentration of As, Bi and Se. The optimum reagent concentration was found to be 0.1%. The elements were determined on the filters by X-ray fluorescence spectrometry. The detection limits achieved were 0.1-4.0 μg of element on the filter. Relative standard deviation (R.S.D.) was not higher than 0.08 while determining 5-50 μg of elements on filter. Accuracy and precision of the technique proposed were evaluated by the analysis of spiked natural samples.     

Photochemical reactions of 7-aminocoumarins.

A number of 3-aryl-4-methyl-7-diethylaminocoumarins were obtained as a result of the photolysis of 3-iodo-4-methyl-7-diethylaminocoumarin in the presence of benzene, chlorobenzene, fluorobenzene, benzonitrile, toluene, and diphenyl ether. On the basis of an analysis of the PMR spectra it was established that photosubstitution leads to o- and p-isomeric products. The mechanism of the reaction was studied.See [1] for Communication 7.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1172–1176, September, 1990.     

Fatty acid composition of the main phospholipids of the Antarctic krill Euphausia superba

The Antarctic krillEuphausia superba Dana contains about 5% of its natural weight of extractable lipids, more than half of which are in the form of phospholipids — phosphatidylcholine (33–36% of the sum of the lipids), phosphatidylethanolamine (15–17%), lysophosphatidylcholine (3–4%), and others (2–3%) — while among the phosphorus-free components triacylglycerols predominate (32–35%). In the first two phospholipids the dominating fatty acid residue is the arachidonic acid residue (more than 40% of the sum of the acyl residues) and the amounts of residues of eicosapentaenoic acid (C_{20 : 5w3}) are about 13 and 28%, respectively. A simple procedure for isolating the phosphatidylcholine and phosphatidylethanolamine is proposed. For the analysis of the fatty acid a new method was used, consisting of the HPLC of their (7-diethylaminocoumarin-4-yl)hydrazides, with fluorometric detection.Scientific Research Laboratory of Biologically Active Substances of Hydrobionts, USSR Ministry of Health, Moscow. K. A. Timiryazev Moscow Agricultural Academy. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 181–187, March–April, 1990.     

Synthesis,spectral-luminescence,and acid-base properties of 3-halo-7-aminocoumarins

The reactions of substituted coumarins with a variety of halogenating agents, leading to the formation of the corresponding 3-chloro-, 3-bromo-, and 3-iodo-7-aminocoumarins, have been studied. It has also been shown, based on the results of studies of the spectral-luminescence and acid-base characteristics of these 3-halo-7-aminocoumarins, that their basicity increases as the electron-donating nature of the substituent in the 4-position increases, and is also greater, as expected, for 3-iodo- and 3-chloro derivatives than for 3-bromo derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1609, December, 1990.     

Efficacy of the academic competition (Olympiad) system of admission to higher educational institutions (in Chemistry)

The association between the academic competition (Olympiad) results and subsequent academic performance during the first two years at a higher educational institution was examined. The data for three cohorts (N = 738) of students of the Chemistry Department, Moscow State University, were analyzed, including the results of international and nationwide academic competitions in chemistry, university grade point averages, and Unified State Examination scores. It was shown that students admitted on the basis of academic competition results (winning or prize-winning) perform significantly better during the first two years at the university than those admitted on the basis of Unified State Examination scores. It was shown that the results of academic competitions of different levels are not equal in predicting subsequent academic performance for students.     

Synthesis of tritium-labeled components of nucleic acids of the hypoxanthine series

The synthesis of [8-³H] and [2,8-³H]hypoxanthine, inosine, inosine 5-mono-, -di-and -triphosphates, and also of 2-deoxy[2,2-8-³H]inosine from the corresponding labeled compounds of the adenine series with the aid of the de-amination reaction is described. De-amination was carried out with sodium nitrite in the presence of acetic acid. In the case of bases and nucleosides, the separation of the reaction mixtures with simultaneous desalting of the final products was achieved by column chromatography on Sephadex G-10 or SE C-25 with elution by water. For nucleotides, the isolation process included chromatography on DEAE-Sephadex A-25 (HCOO^– or Cl^–) and Dowex 1×8 (Cl^–) followed by desalting with the aid of reprecipitation or adsorption on Carboraffin activated carbon. The molar radioactivities of the compounds synthesized amounted to 370–2220 TBq/mole (10–60 kCi/mole) and corresponded to the molar radioactivities of the initial compounds of the adenine series.V. G. Khlopin Radium Institute, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 128–131, January–February, 1987.     

A Study of a Narrow-Band Receiving System of Cold-Electron Bolometers for the 220 and 240 GHz Channels using an Oscillator Based on the High-Temperature YBCO Superconductor

Radiophysics and Quantum Electronics - We present the results of theoretical and experimental studies of the resonant properties of a single cell of a receiving system based on cold-electron...